Current exercise guidelines recommend that adults engage in at least 150 to 300 minutes of moderate-intensity physical activity or 75 to 150 minutes of vigorous-intensity aerobic physical activity (or an equivalent combination of the two) weekly to promote cardiovascular health. However, a 2006 study challenged those recommendations, suggesting that a single weekly bout of vigorous exercise reduced the risk of cardiovascular disease-related death by 40 percent.

The study involved more than 56,000 people who were free of cardiovascular disease at enrollment. Researchers tracked the participants' health for roughly 16 years to assess their activity levels and risk of death from heart disease or stroke.

They found that even a single weekly session of intense exercise, lasting 30 minutes or longer, markedly reduced the risk of dying from heart disease or stroke compared to no exercise at all. Interestingly, exercising more frequently or for longer durations each week didn’t provide additional benefits. Another finding was that as men got older, the protective effect of exercise against cardiovascular death became more pronounced. However, this age-related benefit wasn’t evident in women.

Vigorous-intensity exercise is physical activity that demands a significant and challenging effort, promoting a substantial increase in heart and breathing rates. It requires considerable energy expenditure and typically involves activities like running, cycling at high speeds, or intense aerobics. During vigorous-intensity exercise, a person’s target heart rate is approximately 60 to 85 percent of their maximum heart rate.

These findings from this observational study suggest that even one vigorous, 30-minute or longer workout a week can have substantial cardiovascular health benefits. Current exercise guidelines may need to be revised to account for the effects of HIIT on cardiorespiratory fitness. Learn more about the health benefits of HIIT in this episode featuring Dr. Martin Gibala.

• Read study abstract.